Research On Slug Combination Optimization Of Weak Base Asp Flooding In Xing 12 Block

After years of development,most oil fields in China have entered into the late stage of development with high water cut and high recovery degree.The decline in water flooding production is accelerating,the remaining oil is scattered,it is difficult to tap the potential,and the recovery rate is generally only 30%?40%.The ASP flooding is a kind of oil flooding method developed on the basis of base-polymer flooding and surfactant-polymer flooding,which greatly enhances oil recovery.It can enhance oil recovery by more than 20 percentage points compared with water flooding.It is being gradually promoted and has been identified by Daqing Oilfield as one of the leading technologies to achieve sustainable and stable production.In this paper,starting from the reservoir development and geological conditions of Xing12 Block compound flooding test block,based on the theory of reservoir engineering and enhanced oil recovery,and using the indoor physical simulated flooding experiment as the technical means,aiming at the main problems of Pu I3 reservoir in the pure oil area of Xingnan development block,such as high water flooding degree,high washing intensity,low recovery rate of polymer flooding,etc.,were carried out to study the effect of ASP flooding on the artificial core.Through the experiments of polymer injection capacity evaluation,reservoir base sensitivity evaluation,surfactant interface activity comparison and ASP system performance evaluation,the components suitable for the preparation of ASP system in the test block were selected;Then conduct the indoor physical simulation oil displacement experiment.In the experiment,the method of controlling the horizontal comparison of single variables is adopted to study the effects of the injection concentration of each slug and the injection size of each slug on the recovery efficiency of the compound flooding to determine the most suitable injection scheme for the reservoir of Xing 12 Block compound flooding test block,to achieve the purpose of increasing the thickness of the reservoir,reducing the cost of drug injection,and improving the oil recovery rate.The results of indoor physical simulation experiment show that the optimal injection scheme of chemical agent concentration and slug combination in Xing 12 Block ASP flooding test block is:0.06PV pre-slug(C_P=1800 mg/L)+0.30PV ASP main slug(C_P=2000mg/L,C_A=1.20wt%,C_S=0.30wt%)+0.15PV ASP auxiliary slug(C_P=1800 mg/L,C_A=1.00wt%,C_S=0.10wt%)+0.20PV rear plug(C_P=1600 mg/L),this optimal scheme can enhance the recovery rate of chemical flooding by 17.76 percentage points.In addition,the optimized scheme was further compared and verified on the natural core of the test block.The combination injection scheme of chemical agent concentration and slug size is suitable for the field application of weak base ASP flooding test block in Xing 12 Block.